Showing papers on "Myzus persicae published in 2003"
TL;DR: The life history data of the predator Propylaea japonica Thunberg at 25°C fed on Myzus persicae (Sulzer) were collected in the laboratory and the raw data were analyzed based on the age-stage, two-sex life table.
Abstract: The life history data of the predator Propylaea japonica Thunberg at 25°C fed on Myzus persicae (Sulzer) were collected in the laboratory. To take both sexes and the variable developmental rate among individuals into consideration, the raw data were analyzed based on the age-stage, two-sex life table. The intrinsic rate of increase for P. japonica is 0.1133 d−1. The net reproductive rate is 67.6 offspring and the mean generation time is 37.7 days. To incorporate the age-stage variability of the predation rate with the two-sex life table, the daily predation rate of individual P. japonica of both sexes was collected for each predatory stage. The net predation rate for P. japonica is 1199.5 aphids.
219 citations
TL;DR: cDNAs encoding two acetylcholinesterases (AChEs) were isolated from the peach potato aphid, Myzus persicae, and a single amino acid substitution of Ser431Phe on MpAchE2 was found in the pirimicarb resistant strains.
176 citations
TL;DR: Results suggest that OC-I affects M. persicae through digestive tract targets, but also by reaching the haemolymph, thereby inhibiting extra-digested proteolytic activities and interacting with functions related to aphid reproduction.
164 citations
TL;DR: A significant interaction between aphid species and temperature indicated that the pathogenic nature of an isolate was dependent not only on the target Aphid species but also the temperature conditions of the bioassay.
Abstract: As part of an approach to select potential mycoinsecticides for aphid biocontrol, we investigated the effects of temperature on the growth, germination and pathogenicity of some hyphomycete fungi. Commercially available mycoinsecticides (based on Beauveria bassiana (Balsamo) Vuillemin and Verticillium lecanii (Zimmermann) Viegas) and other isolates of B bassiana, V lecanii, Metarhizium anisopliae (Metschnikoff) Sorokin and Paecilomyces fumosoroseus (Wize) Brown & Smith were evaluated. The rate of in vitro conidial germination of all isolates was slower at 10 and 15degreesC than at 20 and 25degreesC. Similarly, in vitro growth of most isolates was adversely affected at 10 and 15degreesC. The greatest reduction at 10degreesC in rates of conidial germination and colony growth, compared with other temperatures, was for M anisopliae isolates. Germination of V lecanii (isolate HRI 1.72) was fastest at 10degreesC compared with the other fungi. It was also the most pathogenic of three isolates tested against Aphis fabae Scopoli and Myzus persicae Sulzer at 10, 18 and 23degreesC. Generally, A fabae was more susceptible than M persicae to infection by the fungal isolates tested. A significant interaction between aphid species and temperature indicated that the pathogenic nature of an isolate was dependent not only on the target aphid species but also the temperature conditions of the bioassay. The series of studies, detailed above, allowed a temperature profile to be formed for the different isolates. Verticillium lecanii isolate HRI 1.72 (commercialised as Ver-talec(R)) was the most promising isolate selected from results of the series of experiments. Temperature profiles in conjunction with infectivity assays can be useful in selecting appropriate isolates for a particular thermal environment. (C) 2003 Society of Chemical Industry.
152 citations
TL;DR: Experiments on neonicotinoid-susceptible and -tolerant populations of M persicae under simulated field conditions in the laboratory showed that, although the latter were well controlled by imidacloprid applied at recommended application rates, they were more likely to survive and reproduce when this compound was applied at lower concentrations.
Abstract: Laboratory bioassays applying the neonicotinoid insecticides imidacloprid, acetamiprid and nitenpyram against clones of the peach-potato aphid Myzus persicae (Sulzer) demonstrated that these compounds effectively circumvent the known carboxylesterase, modified acetylcholinesterase (MACE) and knock-down (kdr) insecticide resistance mechanisms in this species. However, some clones showed cross-tolerance (up to 18-fold) of these compounds relative to susceptible standards. A survey assessing the frequency of neonicotinoid tolerance in M persicae in the UK, based on samples collected from the field and glasshouses between 1997 and 2000, showed that such tolerance is still rare. Experiments on neonicotinoid-susceptible and -tolerant populations of M persicae under simulated field conditions in the laboratory showed that, although the latter were well controlled by imidacloprid applied at recommended application rates, they were more likely to survive and reproduce when this compound was applied at lower concentrations. Such conditions are probably periodically present in imidacloprid-treated field and glasshouse crops. Selection favouring tolerant forms of M persicae could lead to increases in their frequency and the evolution of more potent resistance to neonicotinoids.
103 citations
TL;DR: The susceptibility to several insecticides of 16 and 8 strains of Myzus persicae Sulzer and Aphis gossypii Glover received from different European countries in 2001 was investigated, finding virtually no resistance to imidacloprid and strong resistance was found to pirimicarb and oxydemeton-methyl, and to a lesser extent also to cyfluthrin.
Abstract: The susceptibility to several insecticides of 16 and 8 strains of Myzus persicae Sulzer and Aphis gossypii Glover, respectively, received from different European countries in 2001 was investigated. Most of the strains were derived from places known for their aphid resistance problems to conventional insecticides before imidacloprid was introduced. In many regions and agronomic cropping systems imidacloprid has been an essential part of aphid control strategies for a decade, and therefore the susceptibility of aphid populations to imidacloprid using FAO-dip tests and diagnostic concentrations in a leaf-dip bioassay was checked. Additional insecticides tested were cyfluthrin (chemical class: pyrethroid), pirimicarb (carbamate), methamidophos and oxydemeton-methyl (organophosphates). Diagnostic concentrations (LC99-values of reference strains) for each insecticide were established by dose response analysis using a new leaf-disc dip bioassay format in 6-well tissue culture plates. Virtually no resistance to imidacloprid in any of the field-derived populations of M. persicae and A. gossypii was detected. In contrast, strong resistance was found to pirimicarb and oxydemeton-methyl, and to a lesser extent also to cyfluthrin. Two strains of A. gossypii exhibited reduced susceptibility to imidacloprid when tested directly after collection. However, after maintaining them for six weeks in the laboratory, the aphids were as susceptible as the reference strain. The diagnostic concentration of methamidophos did not reveal any resistance in M. persicae, but did so in four strains of A. gossypii.
92 citations
TL;DR: Differences in the population structure between reproductive modes suggest that the migration associated with the change of host during sexual reproduction lowers the level of population differentiation.
Abstract: The peach–potato aphid, Myzus persicae (Sulzer), has a complex reproductive mode in which some lineages reproduce by continuous parthenogenesis, whereas others reproduce sexually once a year. The climate is thought to act directly on the reproductive mode, because sexual eggs are the only form that can resist frost in cold regions. Sexual reproduction necessitates an obligatory host alternation that may result in long-distance dispersal. Here, we examined the genetic variability at seven microsatellite loci of populations of M. persicae in France, where both reproductive modes occur. We provide clear genetic evidence that the breeding system affects genotypic variability, as cyclically parthenogenetic aphids are far more variable than their obligately parthenogenetic counterparts. A temporal decrease in genetic variability and a temporal genetic differentiation effect suggest the existence of selective factors that play an important role in shaping the genetic structure of M. persicae populations. Lastly, differences in the population structure between reproductive modes suggest that the migration associated with the change of host during sexual reproduction lowers the level of population differentiation.
89 citations
TL;DR: This study indicates that the pta gene can be used as a supplement to the snowdrop (Galanthus nivalis) lectin gene (gna) in the control of aphids, a sap-sucking insect pest causing significant yield losses of crops.
Abstract: Tobacco leaf discs were transformed with a plasmid, pBIPTA, containing the selectable marker neomycin phosphotransferase gene (nptII) and Pinellia ternata agglutinin gene (pta) via Agrobacterium tumefaciens-mediated transformation. Thirty-two independent transgenic tobacco plants were regenerated. PCR and Southern blot analyses confirmed that the pta gene had integrated into the plant genome and northern blot analysis revealed transgene expression at various levels in transgenic plants. Genetic analysis confirmed Mendelian segregation of the transgene in T1 progeny. Insect bioassays showed that transgenic plants expressing PTA inhibited significantly the growth of peach potato aphid (Myzus persicae Sulzer). This is the first report that transgenic plants expressing pta confer enhanced resistance to aphids. Our study indicates that the pta gene can be used as a supplement to the snowdrop (Galanthus nivalis) lectin gene (gna) in the control of aphids, a sap-sucking insect pest causing significant yield losses of crops.
72 citations
TL;DR: Results from this study suggest not only that at least two strains of SPFMV occur in the United States, but that two other potyviruses also are present.
Abstract: Souto, E. R., Sim, J., Chen, J., Valverde, R. A., and Clark, C. A. 2003. Properties of strains of Sweet potato feathery mottle virus and two newly recognized potyviruses infecting sweet potato in the United States. Plant Dis. 87:1226-1232. Some biological and molecular properties of six potyvirus isolates (LSU-1, -2, -3, and -5; 95-2; and 95-6) from sweet potato (Ipomoea batatas) were evaluated. Isolates LSU-1 and -3 and 95-2 were transmitted by Aphis gossypii and Myzus persicae while LSU-2 and -5 were not transmitted by either aphid. The partial nucleotide sequence of the nuclear inclusion b (NIb) and the coat protein (CP) genes of these six isolates were compared with the corresponding sequences of 17 Sweet potato feathery mottle virus (SPFMV) strains and 18 other potyviruses. LSU-1 and -3 had high sequence similarity to the published sequences for Sweet potato virus G (SPVG), did not react with antisera to other known sweet potato viruses, and caused distinct symptoms. We propose to designate these two isolates as SPVG. This report documents the occurrence of this virus in the United States and provides the first characterization of its biological properties. LSU-2 and -5 were distinct in symptomatology; partial Nib, CP nucleotide, and derived amino acid sequence; and serology to other viruses. We propose to call this virus (LSU isolates 2 and 5) Ipomoea vein mosaic virus. The present study revealed a high degree of sequence similarity between 95-6 and the common strain of SPFMV, and between 952 and the russet crack strain of SPFMV. Results from this study suggest not only that at least two strains of SPFMV occur in the United States, but that two other potyviruses also are present.
69 citations
TL;DR: Aphids from Lehonia had significantly higher mean values for developmental time on tobacco than clones from the other regions whereas the opposite was observed when aphids were reared on pepper.
Abstract: The performance of eighteen clones of Myzus persicae (Sulzer) on pepper and tobacco plants at 20°C and L16:D8 and the choice of young adult apterae between tobacco and pepper leaf-discs were examined. The clones were collected from weeds and peach in two tobacco-growing regions: Katerini, northern Greece and Karditsa, central Greece (only from weeds) and from Lehonia, central eastern Greece where tobacco is not cultivated. All clones did well on both hosts. However, the analysis of data revealed a significant effect of ‘region / host plant origin’ on aphid performance. The mean values of adult weight, intrinsic rate of increase and fecundity of the clones collected in Lehonia and reared on tobacco were significantly lower than the observed values for clones from Katerini and Karditsa. Aphids from Lehonia had significantly higher mean values for developmental time on tobacco than clones from the other regions whereas the opposite was observed when aphids were reared on pepper. Aphids collected in Lehonia performed better on pepper than those originating from the tobacco-growing regions. A choice test revealed differences among the clones originating from different regions. Fifty three percent and 43% of aphids from weeds and peach from Lehonia, respectively, chose pepper. By comparison 41.5% and 40.0% of aphids from peach and weeds from Katerini, respectively and 49.5% of aphids from Karditsa preferred tobacco. The results are discussed in relation to host specialization in M. persicae.
68 citations
TL;DR: The data show that when Arabidopsis plants are infested with a leaf tissue‐damaging Herbivore they emit a volatile blend that attracts C. rubecula females and the wasps only discriminate between a host and non‐host herbivore when the type of damage is different (chewing vs. piercing).
Abstract: In this study we investigated whether in a two-choice set-up the parasitoid Cotesia rubecula (Marshall) (Hymenoptera, Braconidae) distinguishes between volatiles emitted by Arabidopsis thaliana (L.) Heynh. (Brassicaceae) infested with its host, Pieris rapae (L.) (Lepidoptera: Pieridae) and Arabidopsis infested with non-host herbivores. Four non-host herbivore species were tested: the caterpillars Plutella xylostella (L.) (Lepidoptera: Plutellidae) and Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae), both chewing insects, the spider mite Tetranychus urticae (Koch) (Acari: Tetranychidae), which punctures parenchymal cells, and the aphid Myzus persicae (Sulzer) (Hemiptera: Aphidoidea), which is a phloem-feeder. Compared with undamaged plants, C. rubecula females were more attracted to Arabidopsis plants infested by P. rapae, P. xylostella, S. exigua, or T. urticae, but not to plants infested by M. persicae. The parasitoids preferred host-infested plants to spider mite- or aphid-infested plants, but not to plants infested with non-host caterpillars (P. xylostella or S. exigua). The data show that when Arabidopsis plants are infested with a leaf tissue-damaging herbivore they emit a volatile blend that attracts C. rubecula females and the wasps only discriminate between a host and non-host herbivore when the type of damage is different (chewing vs. piercing). When Arabidopsis is infested with a herbivore that hardly damages leaf tissue, C. rubecula females are not attracted. These results may be explained by differences in the amount of damage and in the relative importance of different signal-transduction pathways induced by different types of herbivores.
TL;DR: The role of foliar pubescence in resistance to the aphid was established and information on which types of trichomes most strongly affect resistance to insect pests will aid future breeding and L. pennellii shows potential for use in breeding programs to increase levels of host-plant resistance in L.esculentum.
Abstract: The green peach aphid (Myzus persicae) is becoming resistant to many of the pesticides used in the tomato (Lycopersicon esculentum) industry A potential alternative method of control is host-plant resistance, which may be mediated by trichomes Resistance to the green peach aphid was assessed for six accessions of L hirsutum, three of L pennellii and a L esculentum control Mortality, entrapment and number of aphids unaffected by trichomes were recorded 24, 48 and 72 h after placement Using multiple regression against counts of glandular and non-glandular trichomes, the role of foliar pubescence in resistance to the aphid was established Lycopersicon pennellii possessed the highest level of resistance after 72 h and type IV trichome density accounted for 265% of variance in mortality (P < 0001) Low densities of type IV and high densities of type VII trichomes increased the number of aphids ‘unaffected’ by trichomes, a relationship accounting for 29% of variance (P < 0001) Information on which types of trichomes most strongly affect resistance to insect pests will aid future breeding and L pennellii shows potential for use in breeding programs to increase levels of host-plant resistance in L esculentum
TL;DR: Elimination of UV by UV-absorbing film did not affect the parasitic activity of A. matricariae, which makes the use of UV- absorption films an effective component of IPM that aims to reduce the application of toxic insecticides.
Abstract: Laboratory and field experiments were conducted to study the effect of UV filtration on the population growth, distribution and flight activity of the green peach aphidMyzus persicae (Sulzer) (Homoptera: Aphididae), and on the fecundity and host-finding behavior of the parasitic waspAphidius matricariae (Haliday) (Hymenoptera: Braconidae). The work was done in the Arava Valley of Israel, in walk-in tunnels covered with polyethylene film, to compare the effects of UV-absorbing filmversus those of regular film. Following artificial aphid infestation on pepper grown under the tested films, aphid population growth and spread under the UV-absorbing films were significantly less than under the regular films. The greatest impact of UV-absorbing film on aphid behavior was observed in winter and early spring, when temperature conditions favor aphid development. Elimination of UV by UV-absorbing film did not affect the parasitic activity ofA. matricariae. Previous results had indicated that covering the greenhouse with UV-absorbing films inhibited the invasion of aphids and other insect pests into it. That effect, in combination with those described in the present paper, makes the use of UV-absorbing films an effective component of IPM that aims to reduce the application of toxic insecticides.
TL;DR: The lack of an overall fitness difference between reproductive modes suggests that cyclical parthenogens incur no cost of polyphenism, but neither can they compensate for the cost of sex during the parthenogenetic phase of their life cycle.
Abstract: In parthenogens, selection acts on entire genotypes rather than individual alleles. The general-purpose genotype hypothesis (GPG) predicts that temporally variable environments select for clones with broad ecological tolerances. These general-purpose genotypes should exhibit low fitness variance and high geometric mean fitness across environments. We tested this hypothesis by comparing the fitness of obligately and cyclically parthenogenetic genotypes of the peach-potato aphid, Myzus persicae, on three unrelated host plants. We found genetic variation for the relative performance on different hosts, but no difference in geometric mean fitness between obligate and cyclical parthenogens. Thus, for an environmental variable of major importance to aphids, the GPG hypothesis was not supported. In addition, the lack of an overall fitness difference between reproductive modes suggests that cyclical parthenogens incur no cost of polyphenism, but neither can they compensate for the cost of sex during the parthenogenetic phase of their life cycle.
TL;DR: It is interesting that it is never detected silencing of amplified FE4 genes, possibly because they are at multiple loci and therefore less likely to be subject to synchronous control, but it does suggest that the resistant phenotype in M. persicae is under epigenetic control.
Abstract: Insecticide treatment of the aphid Myzus persicae (Sulzer) has led to the evolution of several insecticide resistance mechanisms, including the detoxification of insecticides by elevated esterases. This results from amplification of one of two closely related esterase genes (E4 or FE4) with up to 80 copies in the most resistant aphids. The amplified E4 genes are at a single site linked to a chromosomal translocation and resistance can be unstable. Individuals within a clone lose their elevated esterase and resistant phenotype, a good example of'clonal variation'. This loss of esterase is accompanied by a loss of the corresponding mRNA but the amplified genes are retained with no detectable sequence differences. However, the expressed E4 genes contain 5-methylcytosine, which is lost at the same time as the genes are turned off. This is in direct contrast with vertebrate genes where DNA methylation causes gene silencing, but it does suggest that the resistant phenotype in M. persicae is under epigenetic control. One hypothesis is that 5-methylcytosine in E4 genes facilitates expression by preventing the production of incorrectly initiated transcripts. It is interesting that we have never detected silencing of amplified FE4 genes, possibly because they are at multiple loci and therefore less likely to be subject to synchronous control.
TL;DR: Molecular and biochemical methods were used to determine the genotypes or phenotypes associated with four insecticide resistance mechanisms in single aphids from sexually-reproducing populations in southern France, finding almost all resistant individuals overproduced FE4 carboxylesterase, whereas modified acetylcholinesterase was rare.
Abstract: Intensive chemical treatments have led to the development of a number of insecticide resistance mechanisms in the peach-potato aphid Myzus persicae (Sulzer). Some of these mechanisms are known to be associated with negative pleiotropic effects (resistance costs). Molecular and biochemical methods were used to determine the genotypes or phenotypes associated with four insecticide resistance mechanisms in single aphids from sexually-reproducing populations in southern France. The mechanisms considered were E4 and FE4 carboxylesterase overproduction, modified acetycholinesterase, and kdr and rdl resistance-associated mutations. A new method for determining individual kdr genotypes is presented. Almost all resistant individuals overproduced FE4 carboxylesterase, whereas modified acetylcholinesterase was rare. Both the kdr and rdl resistance mutations were present at high frequencies in French sexually-reproducing populations. The frequencies of insecticide resistance genes were compared before and after sexual reproduction in one peach orchard at Avignon to evaluate the potential impact of selection on the persistence of resistance alleles in the over-wintering phase. The frequencies of the kdr and rdl mutations varied significantly between autumn and spring sampling periods. The frequency of the kdr mutation increased, probably due to pyrethroid treatments at the end of the winter. Conversely, the frequency of the rdl mutation decreased significantly during winter, probably because of a fitness cost associated with this mutation.
TL;DR: Green tile pan trap counts during the potato-growing season showed thatCapitophorus elaeagni (32%),Diuraphis noxia (27.7%), andMetopolophium dirhodum (15%) were the most abundant aphid species in potato fields at Aberdeen, Idaho.
Abstract: Green tile pan trap counts during the potato-growing season showed thatCapitophorus elaeagni (32%),Diuraphis noxia (27.7%), andMetopolophium dirhodum (15%) were the most abundant aphid species in potato fields at Aberdeen, Idaho.Acyrthosiphon pisum (22%),C. elaeagni (19%), andMetopolophium dirhodum (19%) were the most abundant species in potato fields at Tetonia, Idaho potato seed production areas. Eight species of aphids found to visit potato fields (C. elaeagni, D. noxia, M. dirhodum, Myzus persicae, Rhopalosiphum maidis, Rhopalosiphum padi, Schizaphis graminum, andSitobion avenue) were tested for Potato virus Y (PVY) transmission efficiency by timed probe experiments. Four of these species (D. noxia, M. dirhodum, M. persicae, andS. aoenae) and an additional three (Diuraphis frequens, Diuraphis mexicana, andDiuraphis tritici) were tested using mass inoculations.Capitophorus elaeagni, M. persicae, R. maidis, R. padi, andS. graminum all transmitted PVY in the timed probe experiments.Myzus persicae andD. noxia transmitted PVY in the mass inoculation experiments.
TL;DR: The life parameters of one red and one green clone of Myzus persicae reared on 11 Oriental tobacco type varieties and on five Virginia ones were examined.
Abstract: 1 The life parameters of one red and one green clone of Myzus persicae reared on 11 Oriental tobacco type varieties (KP7, K63, KZ10/z, MA13/b, BX2/a, N34/4, KP14/a, Kolindros, S79, TA21 and BX81) and on five Virginia ones (VE9, VE3, SPG28-VE2, Kleio-KN1 and Niki-NK3) at 20 °C and LD 16 : 8 h were examined.
2 In general, the clones, performed better on Oriental than on Virginia type varieties. The varieties TA21 and Kolindros could be considered as the most resistant among the Oriental ones. Aphids on Virginia varieties showed longer developmental time (9.1–9.6 days), a lower intrinsic rate of increase (0.2347–0.2647) and higher nymphal mortality (27.9–52.5%) than on Oriental varieties. The corresponding values in the latter were 7.3–9.0 days, 0.2784–0.3302 and 10.0–47.9%.
3 The leaves of Virginia type varieties (188–471 hairs/cm2) and one Oriental (K63) 273 hairs/cm2 were more hairy than the other Oriental type varieties (61–150 hairs/cm2). The Virginia type varieties showed also a lower level of reducing sugars (3.5–7.2%) than the Oriental ones (7.0–9.8%). Trichome density and level of reducing sugars were significantly negatively correlated with developmental time and intrinsic rate of increase.
4 An interclonal variation in performance, possibly related to the colour of aphids, was observed. The red clone performed better than the green one. The same trend was observed when the results of the previous clones on the variety KP14/a were analysed with the data obtained on the same variety from two other clones (one red and one green).
TL;DR: Results from these studies highlight the need to discriminate between direct and indirect effects when studying tritrophic interactions between plants/pests/natural enemies and suggest that GNA is not deleterious to ladybirds.
Abstract: Tritrophic interactions between transgenic potato expressing the insecticidal lectin from snowdrop (Galanthus nivalis agglutinin; GNA), an aphid pest, Myzus persicae (Sulz.), and a beneficial predator, the 2-spot ladybird (Adalia bipunctata L.) were investigated. Clonal plants expressing GNA at 0.1-0.2% total soluble protein in leaves were used. No significant effects on development and survival of ladybird larvae fed on aphids from these transgenic plants were observed, with larval survival in the experimental group being 90% compared to 89% for controls. There were also no effects on subsequent female or male longevity. Female fecundity was also investigated. Although no significant differences (p > 0.05) were observed in egg production between control and experimental groups, a 10%, reduction (p < 0.01) in egg viability (determined by % hatch) occurred in ladybirds fed aphids reared on transgenic plants. Additional studies were carried out using aphids fed on artificial diet containing GNA, to deliver quantified levels of the protein to ladybird adults. GNA had no deleterious effects upon adult longevity, but resulted in a consistent trend for improved fecundity. Egg production was increased by up to 70% and egg viability also increased significantly. The results suggest that GNA is not deleterious to ladybirds. Results from these studies highlight the need to discriminate between direct and indirect effects when studying tritrophic interactions between plants/pests/natural enemies. Furthermore, it emphasises the importance of demonstrating 'cause and effect'.
TL;DR: It is demonstrated that CABYV particles are acquired from the gut lumen to the haemocoel through two different sites in both aphid species, i.e. the posterior midgut and the hindgut, which represents an original situation among viruses in the family Luteoviridae examined so far by TEM.
Abstract: Members of the family Luteoviridae (‘luteovirids’) rely strictly on aphid vectors for plant-to-plant transmission. This interaction operates according to a persistent and circulative manner, which implies that the virions are being endocytosed and exocytosed across two epithelial barriers (alimentary tract and accessory salivary glands) in the vector's body. In several luteovirid–aphid vector species combinations, the route of virions in the insect has been investigated ultrastructurally by transmission electron microscopy (TEM). Here, we used TEM to follow the route of Cucurbit aphid-borne yellows virus (CABYV; genus Polerovirus) in its two efficient vector species, Myzus persicae and Aphis gossypii. We demonstrated that CABYV particles are acquired from the gut lumen to the haemocoel through two different sites in both aphid species, i.e. the posterior midgut (as for Beet western yellows virus in M. persicae) and the hindgut (as for Barley yellow dwarf virus complex in cereal aphids). This ‘dual’ tissue specificity of CABYV represents an original situation among viruses in the family Luteoviridae examined so far by TEM. A variety of virion-containing structures (e.g. clathrin-coated and tubular vesicles, endosome-like bodies) are found in intestinal cells of both types in both aphids. Release of virus particles from midgut and hindgut cells into the haemolymph was confirmed by immunotrapping using CABYV-specific antibodies. In accessory salivary glands, transport of CABYV virions across the cells was similar in each aphid species, and occurred by a transcytosis mechanism involving formation of tubular and coated vesicles before release of free virions in the salivary canal.
TL;DR: Reproductive success and response to alarm pheromone, both potentially important components of fitness, were assessed using clones of Myzus persicae to establish associations with insecticide resistance conferred by insensitive modified acetylcholinesterase (MACE).
Abstract: Reproductive success and response to alarm pheromone, both potentially important components of fitness, were assessed using clones of Myzus persicae (Sulzer) to establish associations with insecticide resistance conferred by insensitive modified acetylcholinesterase (MACE). Both traits showed significant trends that were apparently related to this mechanism. MACE forms appeared to reproduce at slower rates than non-MACE forms expressing moderate (111) levels of another resistance mechanism based on elevated carboxylesterase. However, MACE forms were more responsive to alarm pheromone than their non-MACE counterparts. The potential implications for parasitoid performance were tested using two clones showing clear differences in alarm response. The level of parasitism of M persicae by the parasitoid Aphidius colemani (Viereck) was significantly lower in MACE forms on pepper crops compared to non-MACE forms. In addition, the distribution of MACE and non-MACE forms differed on the pepper plants, with more MACE forms being found on the growing points. The presence of the parasitoid A colemani did not alter this change in distribution. (C) 2003 Society of Chemical Industry.
Patent•
23 Sep 2003TL;DR: The genes encoding ryanodine receptor homologs have been characterized from multiple insect families including lepidopteran tobacco budworm (Heliothis virescens), homopteran green peach aphid (Myzus persicae), corn plant hopper (Peregrinus maidis), cotton melon aphid(Aphis gossypii) and fruitfly (Drosophila melanogaster).
Abstract: The genes encoding ryanodine receptor homologs have been characterized from multiple insect families including lepidopteran tobacco budworm (Heliothis virescens), homopteran green peach aphid (Myzus persicae), corn plant hopper (Peregrinus maidis), cotton melon aphid (Aphis gossypii) and fruitfly (Drosophila melanogaster). The full-length genes have been isolated, cloned and amplified in bacterial cells. Expression in insect cells shows that the recombinant protein folds into a functional calcium release channel. The genes and their corresponding polypeptides have a number of uses including, but not limited to, the isolation of other pest ryanodine receptors, the development of screens to identify insecticidally active compounds, use of fragments of genes as pesticides, fragments of protein for antibody production, fragments of protein for determination of the structure of insecticide binding sites, and identification of insecticides that disrupt the calcium balance in cells through other messengers that interact with the receptor calcium release mechanism. Methods are outlined for overcoming toxic effects of expressing recombinant proteins in host cells.
TL;DR: Adult males showed a higher longevity than females in both species and both species completed their nymphal development feeding only on plant juices although they required significantly more time to attain adulthood than when feeding on prey.
Abstract: Biological and population parameters of the predatory bugs Macrolophus costalis Fieber and Macrolophus pygmaeus Rambur preying on the tobacco aphid Myzus persicae (Sulzer) were examined. Tobacco was used as host plant and all experiments were carried out at 23°C and L16:D8. In M. costalis, the developmental time for eggs and the total duration of nymphal instars was 13.1 and 22.2 days and in M. pygmaeus 13.0 and 20.2 days, respectively. Both species completed their nymphal development feeding only on plant juices although they required significantly more time to attain adulthood than when feeding on prey. The longevity of M. costalis females and the preoviposition period were 49.9 and 5.6 days and those of M. pygmaeus were 50.3 and 6.3 days, respectively. Adult males showed a higher longevity than females in both species. The intrinsic rate of increase and the mean total number of eggs laid were 0.0644 and 121 in M. costalis and 0.0615 and 104 in M. pygmaeus, respectively. Mean total aphid consumption by nymphs of M. costalis was 61 aphids, about twice that of M. pygmaeus (37 aphids). Total aphid consumption by a male and female pair of M. costalis and M. pygmaeus until the death of the female was 244 and 285 aphids, respectively. The results of the study are discussed in relation to the impact of the two predatory bugs on tobacco aphid populations.
TL;DR: An excitable medium model was constructed, which provided a robust description of aphid population dynamics in terms of plant development-induced changes in aphid fecundity and temporal change in natural enemy pressure.
Abstract: Populations of many phloem-feeding aphid species in temperate regions increase exponentially in early summer and then 'disappear', usually over a time-scale of a few days, in July. To understand these dynamics, empirical investigation of the causes and modelling of the processes underlying population change are required. Numbers of the aphids Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas), monitored over three years in commercial potato fields in the UK, increased to a maximum of 2-2.5 per leaflet on 16 July in 1999 and 2001, and then declined to < 0.25 per leaflet by 26 July. In 2000, aphid numbers remained very low (< 0.25 per leaflet) throughout the season. The onset of the crash in aphid numbers (16-19 July in 1999 and 2001) was consistently associated with changes in the phloem amino acid composition of potato leaflets. Natural enemies, including syrphids, parasitoids, coccinellids, chrysopids and entomopathogenic fungi, increased in abundance throughout the sampling period. The incidence of winged emigrant aphids prior to the crash was low (< 10%). Experimental manipulation during 2001 demonstrated that, during the crash period, the fecundity of aphids (caged on leaves to exclude natural enemies) was depressed by 25-45% relative to earlier in the season, and that presence of natural enemies reduced aphid numbers by up to 68%. Using these data, an excitable medium model was constructed, which provided a robust description of aphid population dynamics in terms of plant development-induced changes in aphid fecundity and temporal change in natural enemy pressure.
TL;DR: Biological assays showed that MpDNV could be both transmitted transovarially and horizontally via honeydew and saliva and was able to infect whiteflies but not other aphid species tested.
TL;DR: It is concluded that hta could be a novel and promising candidate for plant transgenic engineering against homopteran insect pests.
Abstract: The effects of the hta gene encoding Helianthus tuberosus agglutinin (HTA) on an insect in the order Homoptera were investigated. Homologous cDNAs of hta-a, hta-b, hta-c and hta-d with CaMV35S as promoter were introduced into tobacco via Agrobacterium tumefaciens. Southern blot results showed that the exogenous hta gene was inserted into the genome of host plants, and northern blot analysis confirmed that hta was expressed in transgenic plants. A bioassay with peach-potato aphid (Myzus persicae) demonstrated that transgenic plants had deleterious effects on the insect. The average population of aphids fed on transgenic T0 plants during an 11-day assay decreased by 70%, compared controls. In transgenic plants of T1 generation, aphid fecundity inhibitions were 53.0% (hta-b) and 64.6% (hta-c), respectively. The development of aphids was notably retarded. We conclude that hta could be a novel and promising candidate for plant transgenic engineering against homopteran insect pests.
TL;DR: In this article, the authors investigated potato aphid movement between potato plants early in the season, with a particular focus on their ability to walk over bare soil, and found that the most mobile of the three species was the buckthorn aphid.
Abstract: Potato aphid, Macrosiphum euphorbiae (Thomas); green peach aphid, Myzus persicae (Sulzer); and buckthorn aphid, Aphis nasturtii Kaltenbach are polyphagous herbivores that commonly colonize potato plants, Solanum tuberosum L., in the northeastern United States and Canada. Their movement influences spatial and temporal patterns of viral spread within potato fields. We investigated aphid movement between potato plants early in the season, with a particular focus on their ability to walk over bare soil. On average, aphids survived 1.16 ± 0.04 d (mean ± SE) on the surface of bare soil; all of them dying within 3 d. Wingless aphids did not leave potato plants that were adequate as a food supply. When forcibly removed from the host plant and released on the soil surface, all three species colonized the nearest plant within 1 h. However, when given no other choice, a significant proportion of aphids was fully capable of colonizing potato plants as far as 180 cm away from the point of release. Potato aphid, which is the largest, was the most mobile of the three species. The green peach aphid was intermediately mobile, and the buckthorn aphid was the least mobile species.
TL;DR: The major components of hemolymph were examined by 1H-NMR in seven species of aphids, Acyrthosiphon pisum, A Memphis gossypii, Aphis sambuci, Lachnus tropicalis, Megoura crassicauda, Myzus persicae and Uroleucon nigrotuberculatum.
Abstract: The major components of hemolymph were examined by 1H-NMR in seven species of aphids, Acyrthosiphon pisum, Aphis gossypii, Aphis sambuci, Lachnus tropicalis, Megoura crassicauda, Myzus persicae and Uroleucon nigrotuberculatum Trehalose was detected as the main component from these aphids, and its concentrations in these insects were much higher (196 mM in L tropicalis to 926 mM in A gossypii) than those of two other homopterous insects, Cryptotympana facialis (91 mM) and Nephotettix cincticeps (53 mM) Concentrations in L tropicalis and A gossypii were equivalent to 16% to 20% of the fresh weight Glucose appeared to be an artifact in the hemolymph, because it was not found in the hemolymph when validoxylamine A, a trehalase inhibitor, was added
TL;DR: It is proposed that the chemical cue is most likely in the silk surrounding the parasitoid pupa, and that the mother may leave the chemical in or around the egg at oviposition, inducing chemical defences in her offspring to the secondary plant compounds that the offspring are likely to encounter.
Abstract: The offspring of parasitoids, Aphidius colemani Viereck, reared on Brussels sprouts and emerging from Myzus persicae Sulzer on a fully defined artificial diet, show no preferences in a four-way olfactometer, either for the odour of the diet, the odour of Brussels sprouts, or the odour of two other crucifers (cabbage and Chinese cabbage). A similar lack of odour preferences is shown when the host aphids are exposed for parasitization (for 48 h) on cabbage, Chinese cabbage or wheat. However, if parasitization occurs on Brussels sprouts, a weak but statistically highly significant response to Brussels sprout odour is observed. Although as many as 30-35% of the parasitoids show no response to any odour, another 35% respond positively to the odour of Brussels sprout compared with responses to the odours of cabbage, Chinese cabbage or wheat of only approximately 10%. An analagous result is obtained when the parent parasitoids are reared on cabbage. In this case, significant positive responses of their offspring to cabbage odour occur only if the 48-h parasitization has occurred also on cabbage. However, with parasitoids from Brussels sprouts parasitizing the aphids for 48 h also on Brussels sprouts, the offspring subsequently emerging from pupae excised from the mummies show no preference for Brussels sprout odour. Thus, although the Brussels sprout cue had been experienced early in the development of the parasitoids, they only become conditioned to it when emerging from the mummy. Both male and female parasitoids respond very similarly in all experiments. It is proposed that the chemical cue (probably glucosinolates in these experiments) is most likely in the silk surrounding the parasitoid pupa, and that the mother may leave the chemical in or around the egg at oviposition, inducing chemical defences in her offspring to the secondary plant compounds that the offspring are likely to encounter.
TL;DR: Voracity and prey preference were evaluated for adult females of the predatory bugs Anthocoris nemorum and Anthocoros nemoralis preying upon five species of aphids, of which Myzus persicae Sulzer, Aulacorthum solani, Macrosiphum euphorbiae (Thomas), and Aphis gossypii Glover are common pests in Danish glasshouse crops.
Abstract: Voracity and prey preference were evaluated for adult females of the predatory bugs Anthocoris nemorum (L.) and Anthocoris nemoralis (Fabricius) (Heteroptera: Anthocoridae) preying upon five species of aphids (Homoptera: Aphididae), of which Myzus persicae Sulzer, Aulacorthum solani (Kaltenbach), Macrosiphum euphorbiae (Thomas), and Aphis gossypii Glover are common pests in Danish glasshouse crops. Aphis fabae Scopoli was included to determine the influence of food quality on the preference of the predators, since A. fabae has proved to be of poor nutritional value to Anthocoris spp. The experiments were carried out over 24 h in climate cabinets at 20 °C, 60–70% r.h., L18:D6. The aphids were offered in equal amounts in combinations of two species in instars of comparable size. Myzus persicae served as a reference species in all combinations. Both predators accepted all five species of aphids as prey. The numbers of aphids killed per 24 h period varied between 3.7 and 18.0 for A. nemorum and between 3.6 and 12.7 for A. nemoralis. Field collected A. nemorum females, presumably in a state of reproductive diapause, killed in three of four prey combinations significantly more aphids than did ovipositing A. nemoralis females which originated from a commercial rearing. When A. nemorum females had terminated their reproductive diapause and commenced oviposition, voracity increased approximately threefold. When prey preferences were evaluated as a total number of killed prey, no difference in preference was found between the two Anthocoris species. Both predatory bugs preferred M. persicae to the other species, the most accepted alternative prey were A. gossypii, A. fabae, A. solani, and M. euphorbiae, in descending order. However, evaluating preference by number of aphids consumed, A. nemoralis showed a more pronounced preference for M. persicae, especially when combined with A. fabae. In nearly every case, A. nemoralis rejected A. fabae as a food item after killing the aphid. Thus, A. nemoralis exhibited a more specific food choice than A. nemorum. By killing and consuming different aphid species found in glasshouse crops – particularly M. persicae– both A. nemorum and A. nemoralis showed preliminary qualities as agents for the biological control of aphids.